nRF52832 SPI Master read results in "zeros"

[leey]

Update 1/27/2016

  Just reviewing again the pins + schematic; I am using the following pins:

         SCK     P0.07
         CS       P0.08
         MOSI   P0.06

         MISO    P0.05/AIN3


  Looing at the MISO pin, it seems this is the only one that is "different" than the other 3 pins

  Is there something else that I need to do in order to use MISO pin on P0.05/AIN3; maybe because the pin can also be used as Analog Input ?


  Thanks.

Lee

Hi,

I am interfacing nRF52832 to an ADC chip; very simple SPI interface.

I am re-using the SPI examples from SDK 12.2.0; and the SPI runs without any problem.

I can see the correct signals being generated on the SPI pins(CS, SCK, MOSI and MISO); in regards to MISO pins, I can see the ADC is sending the right bits(using a scope).

The SPI protocol requires: 1x TX byte and will receive 3 bytes of RX data.

On the scope, I can see a total of 32 SCK bits and the correct MISO data.

BUT in the output of the SPI interface APIs, the data read is all "zeros"; so 3 bytes of "0" values.

I have been double checking the codes and can't find any obvious error.

Any suggestion ?

I am attaching the scopes of the 2 pins: SCK and MISO.

Thanks for the help.

scope_3.png

Lee

[Sigurd]

I just tested the spi-master example on the nRF52-DK, with these settings:

//APP_ERROR_CHECK(NRF_LOG_INIT(NULL));

//NRF_LOG_INFO("SPI example\r\n");

nrf_drv_spi_config_t spi_config = NRF_DRV_SPI_DEFAULT_CONFIG;
spi_config.ss_pin   = 8;
spi_config.miso_pin = 5;
spi_config.mosi_pin = 6;
spi_config.sck_pin  = 7;

and it worked just fine.

Also make sure that you are using the correct SPI mode. The default mode is "SCK active high, sample on leading edge of clock".